I have a widget with the data-cards=“hidden” attribute set so that images are not expanded. That used to work OK, but doesn’t now and I notice that the “new improved” embedded timeline docs say that “As part of this redesign, we are also deprecating the old ‘hide media’ option, so all Tweets with media will be expanded by default.”

No, there’s no way to use parameters to hide the images from the new embeds, as we took a decision to respect the original intent of the person posting the Tweet (which would be to include and display the image in the Tweet). There are some jquery recipes that some devs have come up with I think, but they are not officially supported by Twitter.